The invention relates to the replacement of old rail tracks by new ones, and is particularly concerned with the laying of relatively long new rails.
In a known method of replacement, gantries are mounted on the ground or on temporary tracks laid outside the cross-ties, these gantries are used to pick up rail sections and place them on a train. This involves complicated maneuvers, and the gantries have a high center of gravity which leads to instability, and hence an element of insecurity. Furthermore, there is a lack of room to place the new long bars or rails close beside the old track.
It has already been suggested to use a train assembly itself carrying a railway for the gantries or other lifting means. Such a device comprises two rows of rails carried by several linked wagons and forming along the length of the linked wagons a continuous railway for at least one gantry including means for lifting a rail panel (i.e. a unitary rail and cross-tie assembly, forming a section of the old track) through an opening of sufficient size in an open-frame wagon, and transporting the rail panels to another wagon where they are piled. This known device is suitable for the replacement of old panels by new panels of the same uniform and relatively short length, but involves difficulties for replacement by long rails, since whereas for normal, short new rail lengths the front section of the train assembly can run on the old track and the rear section on the new track, without difficulty, the laying of long new rails implies an excessive wheel base, i.e. between the last bogie running on the old track and the first bogie running on the new track.